Photoactive 3D MOFs With pcu Topology for Fluorescence Sensing and Photocatalytic Applications

Abstract

Metal–organic frameworks (MOFs) integrating fluorescence sensing and photocatalytic functions remain challenging to construct due to competing structural requirements. Herein, we report the synthesis, spectral and crystallographic characterization of two novel group organic skeletons composed of 5-(1H tetrazol-5-yl) isophthalic acid (H₃L) ligand (formula [Zn₂L(H₂O)₃]_n⋅nNO₃ (Zn₂L-MOF-1) and [Pb₂L(OH)(H₂O)]_n⋅nH₂O (Pb₂L-MOF-2). Single crystal X-ray analysis shows that Zn₂L-MOF-1 forms an infinite three-dimensional network structure and a double interpenetrating pcu topology through two symmetrical metal centers and a tetrazolium of L³⁻ ligand. Pb₂L-MOF-2 further forms a three-dimensional supramolecular structure through hydrogen bonding between L³⁻ ligand and free water molecules. Zn₂L-MOF-1 can be used as an efficient multifunctional fluorescent material for the high sensitivity detection of metal cations Pb²⁺, Hg²⁺ and nitrobenzene (NB). The minimum limit of detection (LOD) can reach 10⁻⁷ M⁻¹. In addition, Pb₂L-MOF-2 was used as a light-driven catalyst for the photodegradation of tetracycline (TC) antibiotics, with a photodegradation rate of 90.16% within 140 min. The possible sensing and photocatalytic mechanism of MOFs is explained through the comprehensive analysis of experiment and molecular orbital theory. This work establishes photoactive 3D MOFs as dual-purpose materials for environmental monitoring and remediation, with topology-dependent property modulation offering new design paradigms.